1. Department of Electrical and Computer Engineering; Technical University of Munich; Theresienstr. 90 80333 Munich Germany
2. Dipartimento di Scienze e Metodi dell'Ingegneria; UNIMORE; Via Universita 4 41121 Modena Italy
3. Faculty of Science and Technology; Free University of Bozen-Bolzano; Universitätsplatz 1 39100 Bozen-Bolzano Italy